TNG s4e23 “The Host” with shots from DS9 s5e7 “Let He Who Is Without Sin…”
Although the writers of DS9 were obviously aware of the physical differences between Odan and the Trill in DS9, no canon explanation has ever been offered. In an attempt to explain the variations, Terry Farrell once suggested that the spotted members of the species were from the north of Trill whereas Odan was from the planet’s south.
It’s kind of weird it’s never been address given how much the nerds live that sort of continuity.
Hell, they even took her North/South thing and applied it to the Romulans to explain why they looked different in TOS and TNG (although I think it took until PIC to actually say it)
Good luck explaining the difference between the Romulans and Remans.
Vitamin D.
Aren’t remans an unrelated species native to the planet(s) that the romulans colonized after being forced off Vulcan?
From Memory Alpha: